A transparent or semi-transparent glass is commonly used as a window covering material, a partition, a decorative panel and so on. The glass can be painted or colored for a decorative effect. However, the glass has a high density, and is heavy and fragile, and it is difficult to transport and assemble the glass, and the glass is not desirable for safety. Therefore, a transparent resin such as polyvinylchloride or polycarbonate has been used as a substitute of the glass. Polyvinylchloride is not desirable environmentally because undesirable materials are generated during the molding of the polyvinylchloride. In case of the polycarbonate, a drying process is necessary before a molding process, a processing time is relatively long to increase the production cost, and a decorative material (polymer film, paper, fiber fabric, metal wire, metal mesh woven fabric, plant, mineral and so on) can be thermally decomposed in the high temperature thermal molding process, so it is difficult to mold the polycarbonate with the decorative material. Meanwhile, a polyester resin can also be used as the substitute of the glass and as a material (for example, a sheet) capable of including the decorative materials. However, the polyester resin has inferior flexural strength to be easily bent, so it is not desirable as a construction or decoration material. Further, due to the low heat resistance of the polyester resin, the use of the polyester resin is generally restricted to indoor uses.